Rolling mills

ABSTRACT

A four-roll ring rolling apparatus with a pair of rolls for rolling the two curved ring faces and a pair of conical rolls which roll the radial faces of the ring and can be displaced in relation to the ring radially. One roll of each pair of rollers can be fed towards the other radially. At least one roll of each roll pair can be driven. The conical roll pair of rolls is arranged to be automatically displaced in accordance with the increase in the external diameter of the ring owing to the displacement of a feeler roller or the like sensing this diameter at a position adjacent to the pair of rolls, so that it always acts on the radial ring face. The speed of the displacement drive for the conical-roll pair is controlled so as to correspond at least approximately to the speed of increase in ring or hoop diameter. The speed of rotation of the conical-roll pair should be capable of being changed in accordance with the movement of the ring or hoop in relation to the conical rolls in a stepless manner.

United States Patent Wieting ROLLING MILLS [72] Inventor: Eugen Wieting,l-lamm in Westphalia, Germany [73] Assignee: J. BanningAktiengesellschaft,

[51] Int. Cl. ..B2lb 37/00 [58] Field of Search ..72/29, 86, 87, 111,107, 10

[56] References Cited UNITED STATES PATENTS 3,186,202 6/1965 Ulrych..72/10 Oct. 17, 1972 Primary Examiner-Gerald A. Dost Attorney-MalcolmW. Fraser [57] ABSTRACT A four-roll ring rolling apparatus with a pairof rolls for rolling the two curved ring faces and a pair of conicalrolls which roll the radial faces of the ring and can be displaced inrelation to the ring radially. One roll of each pair of rollers can befed towards the other radially. At least one roll of each roll pair canbe driven. The conical roll pair of rolls is arranged to beautomatically displaced in accordance with the increase in the externaldiameter of the ring owing to the displacement of a feeler roller or thelike sensingthis diameter at a position adjacent to the pair of rolls,so that it always acts on the radial ring face. The speed of thedisplacement drive for the conical-roll pair is controlled so as tocorrespond at least approximately ,to the speed of increase inring orhoop diameter. The

speed of rotation of the conical-roll pair should be capable of beingchanged in accordance with the movement of the ring or hoop in relationto the conical rolls in a stepless manner.

9 Claims, 7 Drawing Figures PATENTEDnm 1 1 1972 SHEEI 1 0r 5 INVEINTOR51. m Mw q m a, hip

PATENTEnncI 17 I972 3.6 98.218 sum 2 or 5 FIG. 3

INVENTOR FIGA PATENTEDucI- 1 1 1912 I SHEEI 3 OF 5 PATENTEUum H 19123.698.218

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PATENTEUum :1 I972 3.698 218 SHEET 5 OF 5 INVENTOR @WWZ '4 *JZ d mm. MLM! ROLLING MILLS The present invention relates to rolling mills and moreparticularly to four-roll ring or hoop rolling mills with a pair ofrolls rolling the two curved ring faces and a pair of conical rollsrolling the radial ring or hoop faces.

For the production of rings or hoops, blanks can be made in a press orunder a hammer from billets by upsetting, perforating andpre-broadening. The blanks are made into rings by radial widening insuch four-roll ring rolling mills so that the rolls taken on arectangular cross section or the cross section of a girder. The radialbroadening out of the ring is brought about by the radial roll pairrolling on the two curved ring faces. The radial roll pair comprises aplate roll which is driven and a roll mandril which can be displacedtowards the plate roll in order to adjust the rolling force. The axialrolls engaging the radial faces of the ring serve to achieve therequired dimension of the ring in the axial direction and to remove thedistortion of the radial ring or hoop faces occurring during rolling.The German specification Pat. No. 1,188,544 is concerned with the aim ofproviding a ring or hoop rolling mill with which rings of differentdimensions can be made with a substantial deformation by rolling of theworkpiece in the radial direction and, more particularly, in the axialdirection. The apparatus is intended to make possible the economicworking in accordance with universal rolling programs while achieving asubstantial deformation by rolling in the axial and radial directionswith a high degree of accuracy and standards as regards the shape of thering or hoop produced.

The improved system is used in a ring rolling mill comprising a pair ofrolls for working the two curved ring faces of a ring and a second pairof rolls rolling the radial faces of the ring and capable of beingdisplaced radially in relation to the ring. One roll of each pair ofrolls is capable of being adjusted radially in relation to the other. Atleast one roll of each pair of rolls is driven. The second pair of rollsis arranged to be automatically displaced in accordance with theincrease in the external diameter (by which term is meant the outerdiameter) of the ring owing to the displacement of a feeler roller orthelike sensing this diameter at a position adjacent to the pair of rolls,so that it always acts on the radial ring face. This problem is solvedby provision of a second roll pair consisting of conical rolls and byprovision of a displacement system for the second roll pair withcontrols, which may be electric, hydraulic, etc, including a feelerroll, for displacing the second roll pair back toward the originalrelative position of the conical rolls and the outer diameter of thering.

The present invention also has the object of keeping the slip betweenthe conical rolls and the ring as low as possible. The invention,however, makes use of a completely different principle, base on thefollowing considerations.

Roll slip, that is to say the relative displacement between the axialconical rolls and the radial faces of the ring to be rolled out is,providing there are the same peripheral speeds at the plate rolls and atthe conical rolls running against the exterior diameter of the ring,equal to zero as long as the points of the conical rolls coincide withthe axis of the ring to be rolled. This corresponds to the precisemeshing of two bevel gears.

If now the ring is rolled so as to be thinner against the plate roll byfeeding the roll mandril, the exterior diameter of the ring increasestwice as fast as the axis of the ring moves away.

From this condition results one part of the present invention to theeffect that the speed of the displacement drive of the conical rolls iscontrolled so as to correspond at least approximately to half the speedof increase in ring or hoop diameter.

Such a control arrangement is possible as long as the ring remainswithin the longitudinal extent of the conical rolls, that is to say aslong as the external diameter of the finished ring does not exceed twicethe slant height from base to imaginary geometric vertex of the conicalrolls, hereinafter called the enveloping length of the rolls.

In order to be able to make use of this principle also i in the case oflarger rings, a compromise must be made. In accordance with one featureof the invention the displacement of the conical roll pair is chosen soas to be equal to half the increase of the external diameter of the ringplus the difference between half the increase in the ring size and theincrease in the ring size between the conical rolls.

Since the speed of rolling at the plate roll remains constant, inaccordance with a further feature of the invention the speed of rotationof the conical roll pair should be capable of being changed inaccordance with the movement of the ring or hoop in relation to theconical rolls in a stepless manner.

The invention therefore takes as a basis a four-roll ring or hooprolling apparatus with a pair of rolls for rolling the two curved ringfaces and a pair of conical rolls which roll the radial faces of thering and can be displaced in relation to the ring radially. One roll ofeach pair of rollers can be fed towards the other radially. At least oneroll of each roll pair can be driven. The conical-roll pair of rolls isarranged to be automatically displaced in accordance with the increasein the external diameter of the ring owing to the displacement of afeeler roller or the like which senses this diameter at a positionadjacent to the pair of rolls, so that it always acts on the radial ringface. The speed of the displacement drive for the conical-roll pair iscontrolled so as to correspond at least approximately to half the speedof increase in ring or hoop diameter. The speed of rotation of theconical-roll pair should be capable of being changed in accordance withthe movement of the ring or hoop in relation to the conical rolls in astepless manner.

For the rolling of larger rings or hoops, there is the principle thatthe displacement of the conical roll pair is chosen so as to be equal tohalf the increase of the external diameter of the ring plus thedifference between half the increase in the ring size and the increasein the ring size between the conical rolls.

In the case of the construction in accordance with the Germanspecification Pat. No. 1,188,544, the reverse speed of the displacementdrive for the conicalroll pair was matched so as to agree exactly withthe increase in the diameter of the ring or hoop. In accordance with thepresent invention, the return or reverse speed of this displacementdrive is only so re gulated that the radial faces of the ring remain inengagement with the conical rolls, without a precise or relativelyprecise position in relation to the conical rolls being maintained.Instead a displacement of the radial faces of the ring over theenveloping faces of the conical rolls is intentionally allowed. In orderto avoid excessive slip, the speed of rotation of the conical rolls isautomatically regulated in a stepless manner.

The use of this principle provides a series of advantages.

By fixing the relative position between the conical rolls and the ringthere is a comparatively high degree of wear of the conical rolls inthose parts on which the contact between the conical rolls and theradial faces is located, while the part of the conical rolls which isnot fixed in its relationship to the radial face is only slightly wornor not worn at all. This leads to a local and premature wear of theconical rolls. But when the principle of the present invention is used,the conical rolls are worn over their whole enveloping faces practicallyconstantly. Thus a longer period of service life of the conical rolls isto be expected.

Since, in accordance with the principle of the present invention, at thebeginning of the rolling procedure the conical rolls engage radial facesof the ring with their small-diameter zones, they must be run at ahigher speed, whereby, at the beginning of rolling, the greater power ofthe drive motor is used in a rational manner.

The use of the small-diameter zones of the conical rolls at thebeginning of the rolling procedure furthermore brings with it theadvantage that because of the smaller radius of curvature at thesepositions of the conical rolls, the specific rolling pressure on theradial faces of the ring is greater. That is to say, for a given rollingforce, the rolling action is greater at the beginning of the rollingprocedure.

An important feature which can be adopted in a rolling apparatus or millin accordance with the invention is that, during rolling procedure, thedisplacement drive for the conical roll pair, and therefore the pairitself, is only driven with half, or approximately half, the speed withwhich the increasing outer diameter of the ring grows in the slidedirection of this roll pair.

Thus, if before the beginning of the rolling procedure, this conicalroll pair had a position which was ideal as regards freedom from slip,that is to say so that the imaginary geometrical vertices of the conicalrolls lie on the center line of the ring, this ideal position ismaintained wholly or at least substantially wholly during the rollingprocedure.

Further possible features of the invention, more particularly as regardsthe control means, are set forth in the claims.

The invention is now described with reference to the accompanyingdrawings in more detail.

FIG. 1 shows the rolling of small rings or hoops, the apparatus being inthe position corresponding to the beginning of rolling procedure.

FIG. 2 shows the rolling of small rings, the apparatus being shown inthe position assumed at the end of the rolling procedure.

FIG. 3 shows the rolling of a large ring, the apparatus being shown inthe position assumed at the beginning of the rolling procedure.

FIG. 4 shows the rolling of a large ring, the apparatus being shown inthe position assumed at the end of the rolling procedure.

F IG. 5 shows a rolling mill or apparatus in accordance with theinvention in side view.

FIG. 6 is a plan view of the rolling apparatus in accordance with FIG.5.

FIG. 7 shows the electrical and hydraulic circuitry for the control oroperation of a rolling mill in accordance with the invention.

In FIGS. 1 to 4, corresponding to the symbols used in FIGS. 5 to 7,reference numeral 3 denotes the plate roll, reference numeral 7 denotesthe roll mandril, reference numeral 17 denotes the upper, non-drivenconical roll and reference numeral 14 denotes the lower, driven conicalroll.

FIG. 1 shows the initial position at the beginning of rolling of a ringblank R, which has been placed over the roll mandril 7, and is pressedby the latter against the rotating plate roll 3. The conical rolls 14and 17 roll against the radial faces of the ring R. Ring R is arrangedbetween the front parts of the conical rolls 14 and 17, and has asmaller diameter at the beginning of the rolling process.

During the course of rolling, the end faces of the ring R are displacedalong the enveloping faces of the two conical rolls l4 and 17, the ringblank finally being rolled out to produce the ring R as shown in FIG. 2.The radial faces move along the engaging faces of the conical rolls 14and 17. Care should be taken to see that the tips of the cones, or moreprecisely, the geometric vertex of the illustrated conical frustum ofeach roll, always lie against the center axis of the ring. As can beseen by comparing FIGS. 1 and 2, this center axis moves an amount aoutwards. It is possible to see from FIG. 2 that the tips of the conesalways lie on this center axis. When rolling a ring with this ringdiameter, that is to say as long as the ring diameter is equal to orless than twice the length of the enveloping surface of the conicalrolls, there is no relative slip between the inner and outer diametersand the conical rolls. An additional factor is that, owing to themovement of the radial faces of the ring R, R over the enveloping facesof the conical rolls 14, 17, the latter are evenly worn.

FIGS. 3 and 4 show that the principle of the inven- I tion can also beused for the rolling of ring blanks R to rings R", in which the externaldiameter of the finished ring exceeds twice the length of the envelopingsurfaces of the conical rolls.

The movement of the conical rolls 14 and 17 and the increase in the sizeof the ring are so matched that, at the end of the rolling procedure,the outer circumference of the ring substantially lies against the outeredges of the conical rolls 14 and 17. The displacement of the conicalroll is then equal to half the increment 2a in the external ringdiameter plus the difference a b, a being half the increase in size ofthe ring and b being the increase in dimension in the ring between theconical rolls 14 and 17.

Since the rolling speed on the plate roll 3 remains constant, it isnaturally necessary, in accordance with a feature of the invention, forthe speed of rotation of the conical rolls 14 and 17 to be regulatedsteplessly, while controlling the movement of the conical rolls 14 and17, since the ring continuously changes its position between the conicalrolls as can be seen from the above explanations. The speed regulationof the conical rolls can either be carried out via a steplesslyoperating regulating gear drive or by means of a motor whose speed canbe regulated. In the case of rings with large diameters as well, oneobtains a comparatively small relative slip between the outer and innerring diameters and the conical rolls.

In accordance with FIGS. 5 and 6, the rolling apparatus or mill can beseen to comprise the horizontal rolling stand A and the verticalupsetting or deforming stand B. The king pin 2 with the plate roll isjournalled in the frame 1 common to both parts of the apparatus and isdriven via a transmission 4 by an electric motor 5. The roll mandril 7,which is not driven, is mounted in a slide 6 or carriage which is movedhydraulically in relation to the plate roll. The roll mandril 7 issupported at its upper end by means of the frame-shaped holding device 8which can be swung upwards and lowered hydraulically. At a positionadjacent to the plate roll 3, the guide rolls 9 and 10 are mounted, andthey are pivoted about the shafts 11 and 12 of a hydraulic cylinder formovement of them apart for movement towards the ring to be rolled. Theseguide rolls 9 and 10, with their shafts 11 and 12, can be seen in FIG.6. On the other side of the roll mandril 7, the upsetting frame B can beseen on the roll frame. It is mounted by means which allows sliding. Thesliding movement is brought about by a double acting hydraulic cylinder13. In the bottom part of the upsetting stand or frame B, the lowerconical roll 14 is journalled about a fixed axis. It is driven via astationary gear box 15 by a DC motor 16. The gearbox and the motor areso constructed that the speed of rotation of the conical roll 14 can beso regulated that the peripheral speed of this conical roll can bematched steplessly with the speed of rolling of the plate roll over thewhole length of the enveloping surface of the roll.

The upper conical roll 17 is mounted so that it can rotate freely in acarriage or slide 18, which can be moved for setting by meansof a motorN (not shown in detail) acting through a worm drive 19 and a lead screw20. Besides this adjustment, there is also the possibility of loweringthe slide 18 further downwards hydraulically, for example by about 50 mmso as to exert a force on the ring to be rolled in the axial direction.

Between the conical rolls 14 and 17, the sensing or feeler roll 21 ismounted. It is attached to a rack, which is loaded by a hydraulic piston23 (see also FIG. 7) maintained under constant pressure so that the rackis constantly urged into its advanced, terminal position. The ring,which increases in diameter during rolling, presses the sensing roll 21in a direction corresponding to greater diameter of conical rolls 14 and17. During this movement the rack actuates a ring potentiometer 24 (a,b, and c) with three tracks 24a, 24b and 24c. The first track 24aprovides an input control signal for the drive motor 16 of the lowerconical roll 14. The second track 24b provides the input control signalfor the movement of the axial frame or stand B. In the case of ringswith a diameter which is greater than twice the length of the envelopingsurfaces of the conical rolls 14 and 17, the track 240 of the ringpotentiometer 24 provides an input control signal correction for themovement of upsetting frame B, whereby the ring moves continuouslyduring the rolling procedure over the whole enveloping surface of theconical rolls l4 and 17. When the required ring diameter is attained,the sensing roll is in its retracted terminal position and the rollingprocedure is stopped. As has already been mentioned, optimum slipconditions are thereby obtained for the rolling procedure as regardscontact between the outer and inner diameters of the ring and theconical rolls. The required external diameter of the roll is preselectedat a control console by setting the potentiometer 25, the potentiometer29 being at the upper abutment.

In the frame 1 of the rolling frame'there is a further rack which setsor actuates a ring potentiometer 27 which provides the input controlsignal for the setting of the axial stand B in relation to the axis ofthe plate roll 3. The further double potentiometer 28 serves for settingthe respective diameter of the plate roll 3. This setting is necessarybecause the plate roll is subject to wear; therefore, for preciseregulation of the whole rolling apparatus, the instantaneous valve ofthe diameter of the plate roll must be suitably determined and takeninto account in setting the apparatus.

The potentiometer 29, with the measuring relay 30, is the switching-offpoint for the termination of the rolling procedure by the preselectionof the setting of the sensing or feeler roll 21 between the conicalrolls 14 and 17.

In the case of ring diameters not greater than twice the length of theenveloping surfaces of the conical rolls 14 and 17, the potentiometer 25is set at the lower abutment. In this case the ring diameter is set bythe potentiometer 29.

Since the ring during rolling moves evenly over the whole length of theconical rolls 14 and 17 and the speeds of rolling on the plate r0113 onthe one hand and on the conical roll 14 on the other must be equal inorder to preserve the circular shape of the ring, the speed of rotationof the conical roll 14 must be changed steplessly in accordance with theinstantaneous position of the ring between the conical rolls 14 and 17.

For this purpose the motor 16 of the axial stand B is supplied with thefollowing input control signals:

a. the setting of the feeler roll 21 and thus of the diameter of theconical rolls, by means of the potentiometer track 24a;

b. the output speed of rotation signal of the main motor 5 via thetachometer generator 34.

Thus any change in diameter of the plate roll 3 is fed by thepotentiometer 32, which is mechanically coupled with the potentiometer28, as a correction value or signal into the regulating system.Furthermore the change in the diameters of the conical rolls 14 and 17,which is due to trueing the conical rolls when they become worn, is fedas a further correction value by the potentiometer 33. The output signalin respect of the speed of rotation of the motor 16 is measured by thetachometer generator 31.

The adjustment of the axial stand B is, in principle, anelectro-hydraulic following regulation system. A Wheatstone bridge,consisting of the resistors 35, 24b, and 36 in one limb and theresistors 37, 28a, 27, 28b and 38 in another limb is brought out ofbalance by the response of the feeler roll 21. The voltage resulting inthe null branch between 24b and 27 is evaluated by a null amplifier 39.The output voltage of the null amplitier 39 actuates an electricallyoperated hydraulic servo value 40 which moves the axial stand B untilthe Wheatstone bridge is again brought into balance by the potentiometer27. ln the case of rings which are greater than twice the length of theenveloping surfaces of the conical rolls 14 and 17, the voltage is addedto the input voltage of the null amplifier, which is dependent upon thediameter of the finished ring fed in via the potentiometer 25 andsupplied in accordance with the position of the feeler roller 21 betweenthe conical rolls 14 and 17 via the potentiometer 240. This addedvoltage causes the axial stand B to have to move a distance greater thanthe travel of the sensing roll 21 in order to bring the Wheatstonebridge into balance.

The movement of the axial stand B is brought about by a differentialhydraulic cylinder 13 with a piston space 13a and an annular space 13b.The cylinder receives oil from the pump 41 which, when the axial stand Bis stationary, circulates freely via the safety valve 42. On movement ofthe axial stand B towards the roll mandril 7 at the beginning of rollingprocedure, this valve 42 is closed and the solenoid valve 43 is broughtinto the right-hand position so that the pumps oil into the piston space13a and oil also passes from 13b into 130. On movement of the axialstand away from the roll mandril 7 at the end of rolling the safetyvalve 42 is closed again and the solenoid valve 43 returns back into theleft-hand position. As a result the pump pumps oil into the space 13b,while the space 13a is connected with the hydraulic oil container forthe free discharge of oil. In the setting for regulation during rolling,the valve 42 is closed and the solenoid valve 43 is in the centralposition. The pump conveys oil into the space 13b. However, hydraulicoil forced out of the piston space 13a is controlled via the servo valve40 and the electrical regulation means in such a manner that the axialstand is moved away from the roll mandril 7 only with the speeddetermined by the regulation means.

I claim:

1. In a ring rolling machine for rolling an annular ring blank which hasa center axis, inner and outer peripheral surfaces, and two axial endfaces, wherein the machine comprises:

A. roller means for engaging and rolling said peripheral surfaces,

B. a pair of conical rollers for engaging and rolling respectively thetwo end faces, and

C. sensing means for mechanically determining the position of saidcenter axis and the corresponding outer radial dimensions of the ringblank, the improvement comprising:

D. means responsive to the sensing means for displacing said conicalrollers at such a rate that the geometrical vertices of the conicalrollers remain substantially on said center axis as said radialdimensions increase,

whereby a substantial portion of the surface of the conical rollers maybe used to engage and roll the end faces of rings which remain, at theirgreatest radius, within the longitudinal extent of the conical rollers,as measured from the geometrical vertices.

2. A machine according to claim 1 wherein said sensing means is a feelerroller for continuously sensing the diameter of the ring blank at aposition adjacent to the pair of rolls by feeling the outer peripheralsurface.

3. A machine according to claim 2 further compris- A. a firstpotentiometer means responsive to the feeler roller for supplying asignal representing speed of rotation for use in controlling the drivespeed of the conical rollers B. a second potentiometer means responsiveto the feeler roller for supplying a signal representing ring diameterfor use in controlling the displacement drive of the conical rollers 4.In a ring rolling machine for rolling an annular ring blank which has acenter axis, inner and outer peripheral surfaces, and two axial endfaces, wherein the machine comprises:

A. roller means for engaging and rolling said peripheral surfaces,

B. a pair of conical rollers for engaging and rolling respectively thetwo end faces, and

C. sensing means for mechanically determining the position of saidcenter axis and the corresponding outer radial dimensions of the ringblank, the improvement comprising D. means responsive to the sensingmeans for displacing said conical rollers at such a rate that thedistance between the geometrical vertices of the conical rollers and thecenter axis remains equal to the difference (a-b) between half theincrease in ring size l/2(2a) and the increase (b) in ring size betweensaid conical rollers.

whereby a substantial portion of the surface of the conical rollers maybe used to engage and roll the end faces of rings which, at theirgreatest longitudinal extent, have a radius which exceeds the engaginglength of the conical rolls.

5. A machine according to claim 4 wherein said sensing means is a feelerroller for continuously sensing the diameter of the ring blank at aposition adjacent to the pair of rolls by feeling the outer peripheralsurface.

6. A machine according to claim 5 further comprismg:

A. a first potentiometer means responsive to the feeler roller forsupplying a signal representing speed of rotation for use in controllingthe drive speed of the conical rollers B. a second potentiometer meansresponsive to the feeler roller for supplying a signal representing ringdiameter for use in controlling the displacement drive of the conicalrollers.

7. A machine according to claim 6 further comprisa third potentiometermeans responsive to the feeler roller for supplying a correction signalfor controlling the displacement drive of the conical rollers.

8. A machine according to claim 6 further compris- A. a tachometer meansfor supplying a signal proportional to the speed of rotation of saidconical rollers, and

B. rotational drive means for said conical rollers responsive to saidsignal proportional to the speed of rotation of said conical rollers andto said signal representing speed of rotation for feedback control ofsaid drive means.

9. A machine according to claim 3 further comprising:

A. a tachometer means for supplying a signal proportional to the speedof rotation of said conical rollers, and

B. rotational drive means for said conical rollers responsive to saidsignal proportional to the speed of rotation of said conical rollers andto said signal

1. In a ring rolling machine for rolling an annular ring blank which hasa center axis, inner and outer peripheral surfaces, and two axial endfaces, wherein the machine comprises: A. roller means for engaging androlling said peripheral surfaces, B. a pair of conical rollers forengaging and rolling respectively the two end faces, and C. sensingmeans for mechanically determining the position of said center axis andthe corresponding outer radial dimensions of the ring blank, theimprovement comprising: D. means responsive to the sensing means fordisplacing said conical rollers at such a rate that the geometricalvertices of the conical rollers remain substantially on said center axisas said radial dimensions increase, whereby a substantial portion of thesurface of the conical rollers may be used to engage and roll the endfaces of rings which remain, at their greatest radius, within thelongitudinal extent of the conical rollers, as measured from thegeometrical vertices.
 2. A machine according to claim 1 wherein saidsensing means is a feeler roller for continuously sensing the diameterof the ring blank at a position adjacent to the pair of rolls by feelingthe outer peripheral surface.
 3. A machine according to claim 2 furthercomprising: A. a first potentiometer means responsive to the feelerroller for supplying a signal representing speed of rotation for use incontrolling the drive speed of the conical rollers B. a secondpotentiometer means responsive to the feeler roller for supplying asignal representing ring diameter for use in controlling thedisplacement drive of the conical rollers
 4. In a ring rolling machinefor rolling an annular ring blank which has a center axis, inner andouter peripheral surfaces, and two axial end faces, wherein the machinecomprises: A. roller means for engaging and rolling said peripheralsurfaces, B. a pair of conical rollers for engaging and rollingrespectively the two end faces, and C. sensing means for mechanicallydetermining the position of said center axis and the corresponding outerradial dimensions of the ring blank, the improvement comprising D. meansresponsive to the sensing means for displacing said conical rollers atsuch a rate that the distance between the geometrical vertices of theconical rollers and the center axis remains equal to the difference(a-b) between half the increase in ring size 1/2(2a) and the increase(b) in ring size between said conical rollers. whereby a substantialportion of the surface of the conical rollers may be used to engage androll the end faces of rings which, at their greatest longitudinalextent, have a radius which exceeds the engaging length of the conicalrolls.
 5. A machine according to claim 4 wherein said sensing means is afeeler roller for continuously sensing the diameter of the ring blank ata position adjacent to the pair of rolls by feeling the outer peripheralsurface.
 6. A machine according to claim 5 further comprising: A. afirst potentiometer means responsive to the feeler roller for supplyinga signal representing speed of rotation for use in controlling the drivespeed of the conical rollers B. a second potentiometer means responsiveto the feeler roller for supplying a signal representing ring diameterfor use in controlling the displacement drive of the conical rollers. 7.A machine according to claim 6 further comprising: a third potentiometermeans responsive to the feeler roller for supplying a correction signalfor controlling the displacement drive of the conical rollers.
 8. Amachine according to claim 6 further comprising: A. a tachometer meansfor supplying a signal proportional to the speed of rotation of saidconical rollers, and B. rotational drive means for said conical rollersresponsive to Said signal proportional to the speed of rotation of saidconical rollers and to said signal representing speed of rotation forfeedback control of said drive means.
 9. A machine according to claim 3further comprising: A. a tachometer means for supplying a signalproportional to the speed of rotation of said conical rollers, and B.rotational drive means for said conical rollers responsive to saidsignal proportional to the speed of rotation of said conical rollers andto said signal representing speed of rotation for feedback control ofsaid drive means.